This is a continuation of International Application No. PCT/US94/04109, with an international filing date of Apr. 14, 1994.
1. Field of the Invention
This invention relates to a trailing arm structure in a trailing arm suspension for heavy duty vehicles.
2. Description of Related Art
Heavy-duty vehicle suspension systems are typically characterized by high-strength components, which are relatively heavy. It is desirable to reduce the weight of the suspensions without loss of strength in order to more efficiently carry loads and lower fuel costs.
Trailing arm suspensions are well known. Such suspensions typically comprise a frame bracket, also known as a hanger bracket, that is secured to the frame on each side of the vehicle and a trailing arm, pivotally mounted at one end to each frame bracket and extending rearwardly therefrom. An air spring is mounted between the other end of each trailing arm and the vehicle frame. The trailing arms support a vehicle axle at rigid or semirigid connections with the trailing arms.
Raidel, in U.S. Pat. No. 4,465,298, issued Aug. 14, 1984, discloses a trailing arm suspension having a torque beam with two horizontally displaced members connected by a vertical member. The horizontal and vertical members are extruded hollow rectangular beams having varying dimensions in the various members. Although the beam appears to function properly, the extruded construction is relatively expensive and unnecessarily adds to the cost of the suspension.
Bird, in U.S. Pat. No. 3,547,215, issued Dec. 16, 1970, discloses a trailing arm suspension with a box-beam trailing arm comprising four plates, a top plate, bottom plate, and opposing side plates, welded together to form the trailing arm. Bird requires at least four longitudinal welds to assemble the beam portion of the trailing arm.
Wallace et at., in U.S. Pat. No. 4,858,949 issued Aug. 22, 1989, discloses a trailing arm suspension with a trailing arm having an I-beamlike construction. The I-beamlike construction requires that the trailing arm be cast or forged rather than fabricated from separate pieces.